+static void acm_tty_flush_chars(struct tty_struct *tty)
+{
+ struct acm *acm = tty->driver_data;
+ struct acm_wb *cur = acm->putbuffer;
+ int err;
+ unsigned long flags;
+
+ acm->putbuffer = NULL;
+ err = usb_autopm_get_interface_async(acm->control);
+ spin_lock_irqsave(&acm->write_lock, flags);
+ if (err < 0) {
+ cur->use = 0;
+ goto out;
+ }
+
+ if (acm->susp_count)
+ usb_anchor_urb(cur->urb, &acm->delayed);
+ else
+ acm_start_wb(acm, cur);
+out:
+ spin_unlock_irqrestore(&acm->write_lock, flags);
+ return;
+}
+
+static int acm_tty_put_char(struct tty_struct *tty, unsigned char ch)
+{
+ struct acm *acm = tty->driver_data;
+ struct acm_wb *cur;
+ int wbn;
+ unsigned long flags;
+
+overflow:
+ cur = acm->putbuffer;
+ if (!cur) {
+ spin_lock_irqsave(&acm->write_lock, flags);
+ wbn = acm_wb_alloc(acm);
+ if (wbn >= 0) {
+ cur = &acm->wb[wbn];
+ acm->putbuffer = cur;
+ }
+ spin_unlock_irqrestore(&acm->write_lock, flags);
+ if (!cur)
+ return 0;
+ }
+
+ if (cur->len == acm->writesize) {
+ acm_tty_flush_chars(tty);
+ goto overflow;
+ }
+
+ cur->buf[cur->len++] = ch;
+ return 1;
+}
+